1. Field of the Invention
The present invention relates to a semiconductor device employing an insulation film formed based on an insulation film-forming method and a manufacturing method of a semiconductor device employing this forming method.
2. Description of Related Art
Conventionally, gate insulation films comprising SiO.sub.2 used in the construction of MOS-type transistors are formed by thermally oxidizing a silicon semiconductor substrate. Insulation films comprising SiO.sub.2 formed by thermal oxidation techniques have extremely preferable surface boundary techniques i.e. low surface boundary level density and are a foundation of current semiconductor device manufacturing processes. Alternatively, an insulation film or inter-layer insulation film comprising SiO.sub.2 may be formed by a thermal chemical vapor deposition technique (thermal CVD technique).
While, on the one hand, gate insulation films, insulation films or inter-layer insulation films (hereinafter, these may also be given the name "insulation films, etc.") comprising SiO.sub.2 formed by thermal oxidation or thermal CVD techniques posses superior electrical characteristics, the film-forming temperature is extremely high. i.e. in thermal oxidation, heating a silicon semiconductor substrate temperature of 1000.degree. C. or more is necessary while with thermal CVD techniques, heating a silicon semiconductor substrate to a temperature of 600.degree. C. or more is necessary.
Therefore, when making semiconductor devices where low temperature processes depending on the materials used are applied in the manufacturing of thin-film transistors etc. made on glass substrates, these thermal oxidation techniques and thermal CVD techniques are not appropriate.
On the other hand, plasma CVD techniques may be used as a method of forming insulation films etc. comprising SiO.sub.2 at low temperatures. In these plasma CVD techniques, SiO.sub.2 generated by breaking down SiH.sub.4, N.sub.2 O or O.sub.2 gas using RF discharge is piled onto the surface of a board comprising, for example, a glass substrate. The piling of an insulation film or the like comprising SiO.sub.2 onto the surface of a board at temperatures of 300.degree. C. or less is possible with these plasma CVD techniques. However, high-energy plasma is generated during film-forming with these plasma CVD techniques. The material which the board is made up of, for example, silicon, therefore incurs damage due to the high energy plasma while a gate insulation film comprising SiO.sub.2 is being formed and the manufacturing of a transistor having desirable current/voltage characteristics is no longer possible.